fix(radio): expire idle ICY connections

Pooled keep-alive connections from failed ICY attempts lingered
until the station closed them (observed live against zeno.fm);
bound the idle pool.

Signed-off-by: hiyukoim <11803292+hiyukoim@users.noreply.github.com>

core/radio/provider.go

@@ -19,6 +19,8 @@ var icyHTTPClient = &http.Client{
 		}).DialContext,
 		TLSHandshakeTimeout:   10 * time.Second,
 		ResponseHeaderTimeout: 30 * time.Second,
+		IdleConnTimeout:       60 * time.Second,
+		MaxIdleConnsPerHost:   1,
 	},
 }